Method of making an electrical connection



Aug. 31, 1965 G. USTlN 3, METHOD OF MAKING AN ELECTRICAL CONNECTION Original Filed Jan. 7,1960

s W. F

es INVENTOR.

H GEORGE USTIN 2 O4 ATTORNEY United States Patent f 3,203,078 METHOD F MAKHQG AN ELEQTRECAL @GNNECTION George Ustin, Verona, NHL assignor to Buchanan Electrical Products Corporation, Hillside, NJ., in corporation of New Jersey Continuation of application Ser. No. 1,084, Jan. 7, 1960. This application fan. 4, 1963, Ser. No. 249,533 2 (Ilaims. ((Cl. 29-15555) This invention relates to the formation of insulated electrical connections and particularly to a method for effecting permanent insulated electrical connections by symmetrical deformation of a pre-insulated fitting.

This application is a continuation of my application Serial No. 1,084 filed January 7, 1960, now abandoned.

The commercial formation of insulated spliced or terminated connections of pigtail leads is conventionally effected by either a so-called single step or double step operation. The single step operation requires utilization of a pre-insulated fitting, generally formed of an open ended thimblelike insulator member suitably formed of plastic material such as nylon and a contained metal sleeve, into which the leads to be connected are inserted and the subjection of the workpiece as so assembled to a crimping operation. In the conventional double step operation, the leads to be connected are initially inserted into a metal fitting and subjected to a crimping operation and, subsequently thereto, the crimped workpiece is inserted into an insulating fitting.

Although the above described single step operation possesses obvious inherent manufacturing economies, full realization thereof has not been obtained by the commercial utilization of conventionally constructed crimping tools to effect the required crimping operation. In conventionally constructed crimping tools, such as the general type disclosed in my U.S. Patent No. 2,991,675, deformation of the contained metal sleeve and concommitant deformation of the surrounding insulator is effected by the converging radial advance of a plurality of crimping dies and the necessary degree of die advance required for deformation of the contained metal sleeve has resulted in an undue frequency of destructive perforation of the surrounding insulator member and in a consequent undue number of defective and hence rejected units.

In such conventionally constructed multi-indentor crimping tools, the crimping die tips are shaped to provide maximum penetration in response to application of moderate pressures and consequent deformation of the splicing member material surrounding the conductors. For insulated fittings, the usual insulating material is of appreciably lesser ductility than the metallic fitting member and, as such, are often subject to thinning out, fracture and even perforation in response to suflicient crimping die or indentor penetration to effect the desired deformation of the metallic fitting member.

The invention may be briefly described as a novel method for effecting the necessary deformation of preinsulated fittings in the formation of insulated electrical connections and which minimizes, if not actually eliminates, undesired and destructive insulator perforation.

Among the advantages attendant the invention described herein is the provision of a method for effecting the desired deformation of pro-insulated fittings, the permitted realization of the manufacturing economies inherent in the single step formation of insulated electrical connections, the minimization, if not actual elimination, of the hazards of insulator perforation, and the provision of a novel mode of operation including the effecting of workpiece deformation by a wiping action wherein the point of pressure application varies with the amount of pressure applied.

3,203,073 Patented Aug. 31, 1965 An object of this invention is the provision of a novel and improved method for effecting the deformation of preinsulated fittings in the formation of insulated spliced or terminated electrical connections.

Another object of this invention is the provision of a method for effecting deformation of a pre-insulated fitting by a wiping action wherein the point of pressure application varies with the amount of pressure applied.

Another object of this invention is the provision of a method which can be performed with the aid of a simple and inexpensive tool for deforming insulated fittings with a minimization, if not actual elimination, of the hazards of insulator perforation.

A further object of this invention is the provision of a novel method to permit substantially complete realization of the manufacturing economies inherent in the aforesaid single step fabrication of insulated spliced or terminated electrical connections.

The above and other objects and advantages of the invention will appear from the following specification and claims and from the appended drawings which illustrate the principles of the invention and the essentials of a presently preferred embodiment of a manually operable tool useful in performing the invention.

Referring to the drawings:

FIGURE 1 is a plan view, partly in section, of the essentials of a simple manually operable tool useful in performing the invention; FIGURE 2 is a plan view, partly in section, of the tool shown in FIGURE 1, and showing the positional disposition of the component elements thereof at the point of initiation of a cycle of operation;

FIGURE 3 is an enlarged schematic view showing the disposition of the workpiece deforming elements at or near their limit of workpiece deforming displacement;

FIGURE 4 is a schematic exploded view, partly in section of the general type of pro-insulated fitting that may serve asa workpiece for tool operation;

7 FIGURE 5 is a side elevational view of a workpiece that has been subjected to the operation of the tool described herein.

Referring to the drawings and particularly to FIG- URES 1 and 2, where there is shown by way of illustra tive example, the essentials of a manually operable tool useful in performing the invention, there is provided an underlying plate member 10 having an integral circular raised boss 12 disposed inwardly of the periphery thereof and surrounding an axially disposed circular recess or opening 14 forming a portion of a workpiece receiving and positioning bore. The periphery 16 of the raised boss 12 is concentric with the circular defining wall of the recess 14 and both are centered at a point 18 which serves to define the longitudinal axis of the workpiece receiving and positioning bore in an assembled unit. The plate member 10 is provided with an integral extending handle portion 20 of increased thickness as defined by the diagonally disposed shoulder 22 and is desirably provided with a resilient insulating grip 24.

Mounted on the surface of the raised boss 12 and extending upwardly therefrom are a plurality (three in the specifically illustrated embodiment) of mounting pins 26. The mounting pins 26 are positioned in equi-angular relation relative to the point 18 and in equi-spaced relation relative to each other and to said point 18 and as such are symmetrically disposed about the workpiece receiving and positioned bore. Pivotally mounted on each of the mounting pins 26 so as to be displaceable in a plane disposed substantially perpendicular to the longitudinal axis of the workpiece receiving and positioning bore is a workpiece deforming element or die generally designated 30. Each of the workpiece deforming element 30 includes an outwardly extending actuating arm portion 32 sized to extend beyond the periphery 16 of the boss 12 and an offset or angularly disposed workpiece engaging arm portion 34 having a selectively shaped workpiece engaging surface 36 disposed in facing relationship with the workpiece receiving bore. More specifically, the illustrated workpiece engaging surface 36 is arcuate in configuration, preferably in the shape of a sector having a center disposed at an obtuse angle relative to the longitudinal axis of the extending arm portion 32. Each arcuately or sector shaped workpiece engaging surface is positioned to sweep in an arcuate path and to arcuately traverse a portion of the workpiece receiving and positioning bore in response to pivotal displacement of the workpiece deforming elements 30 about their respective mounting pins 26.

In the illustrated tool the necessary pivotal displacement of the workpiece deforming elements 30 is effected by means of an annularly shaped operating member 40 rotatably disposed in encircling engagement with the periphery 16 of the boss 12 and having an integral extending handle portion 42 of increased thickness as defined by the shoulder 44 and suitably covered with a resilient insulated grip 45. The boss abutting inner surface of the operating member 40 is provided with a plurality of equispaced recesses 46 sized to engage and contain the extending end portions 47 of the actuating arms 32 of the workpiece deforming elements 30. Rotative displacement of the operating member 40, in the clockwise direction as viewed in FIGURE 2 as would be effected by converging handle displacement relative to the plate and boss 12 will effect a concomitant clockwise pivotal displacement of the workpiece deforming elements 30 about the mounting pins 26 and in converging arcuate advance of the arcuately shaped workpiece engaging surfaces 36 and consequent progressive traversion of a portion of the workpiece receiving bore thereby. Rotative displacement of the operating member 40 in the opposite direction, i.e. counter-clockwise as viewed in FIGURE 2, effects a concomitant counter-clockwise pivotal displacement of the workpiece deforming element 30 about the mounting pins 26 and in withdrawal of the arcuately shaped workpiece engaging surfaces 36 from said bore.

Limitation of counter-clockwise displacement of the operating member 40 and maintenance of the above described tool elements in assembled operative position is conveniently effected by a housing plate 50 secured by a plurality of selectively located bolts 52 to the raised boss 12 on plate member 10. As illustratively shown in FIG- URE 2, the bolts 52 are selectively located in the path of rotative displacement of the workpiece engaging arm portions 34 of the workpiece deforming elements 30 and conveniently serve to limit counter-clockwise displacement thereof and of said operating member 40 by abutting engagement therebetween. Clockwise displacement of the workpiece deforming elements 30 may be limited at the point of interengagement of the workpiece deforming elements 30 or any desired location short of actual interengagement thereof, by selective location of the shoulders 22 and 44 on the handle members so as to permit the abutting interengagement thereof to serve as a stop for handle convergence. The housing plate 50 is provided with a circular workpiece receiving aperture 48 disposed concentric with the aperture 14 and cooperating therewith to define the workpiece receiving and positioning bore adapted to permit workpiece insertion from either side of the tool. I

FIGURE 4 is an exemplary exploded view that is intended to be generally illustrative of the essentials of the type of pre-insulated fitting herein of concern. As there shown, the pre-insulated fitting includes a thimblelike insulator member or sleeve 60 having a reduced diameter dependent end portion 62 sized to closely contain a metallic sleeve or ferrule 64 of conducting material as by molding thereabout.

In operation of the described tool the bared ends 68 of the wires to be connected are inserted into the metallic sleeve 64 disposed within the reduced diameter dependent end portion 62 of the pre-insulated fitting to form a workpiece. The handle members 20 and 42 of the tool are then separated to rotatably displace the workpiece deforming elements 36 out of the workpiece receiving and positioning bore to clear the same and permit insertion of the above described assembled workpiece therein. After workpiece insertion through the aperture 48 and reception of the dependent end thereof Within the aperture 14, the handle members 26 and 42 are manipulated in a converging direction to efiect a clockwise rotation of the operating member relative to the plate 10 and boss 12. The clockwise rotation of the operating member 40, due to the disposition of the ends 47 of the actuating arms 32 within the recesses 46, effects a concomitant clockwise and simultaneous rotative displacement of the workpiece deforming member 36 about the mounting pins 26.

It should be noted that the above described construction embodies automatic positioning of the workpiece. Depth control of workpiece insertion is effected by engagement of the shoulder 66 on the workpiece with the defining edge of the receiving bore aperture and transverse positioning thereof is efiected by the simultaneous converging advance of the workpiece deforming elements 30.

The clockwise rotative displacement of the workpiece deforming elements 36 about the mounting pins 26 results in a concomitant inverted arcuate displacement relative to the workpiece periphery of the arcuately or sector shaped workpiece engaging surfaces 36 along a circular path centered at the mounting pins 26 that intersect the workpiece positioning bore, as illustrated by the dotted lines 100 on FIGURE 3.

Additionally, each point on the workpiece engaging surfaces travels along a discrete individual and different arcuate path relative to the axis of the workpiece receiving bore.

The aforedescribed arcuate displacement of the workpiece engaging surfaces 36 thus results in a progressive occupation of a predetermined portion of the workpiece receiving and positioning bore thereby and consequent deformation of a workpiece positionable therein. Although the mechanics of the deformation are not fully understood at the present time, apparently the described inverted arcuate displacement of the sector shaped workpiece engaging surfaces 36 relative to the axis of the workpiece receiving bore, and the abutting engagement of the convexedly disposed surfaces of a workpiece and the workpiece engaging surfaces results in workpiece deformation by a wiping action in contradistinction to the radially applied direct pressure utilized employed in conventionally constructed crimping tools. This wiping action is noticeable both during the initial stages of pressure application and in the resultant deformed workpiece. In the initial stages of pressure application the workpiece may be rotated slightly and apparently indicates the presence of a turning moment. Workpiece rotation apparently ceases soon after initial deformation and subsequent deformation apparently proceeds with the locus of maximum applied pressure apparently varying with the degree of pivotal displacement of the workpiece deforming elements. The nature of the wiping action is also apparent through examination of a workpiece subjected to action of the described tool. As illustrated in FIGURES 3 and 5 there is a generally concave deformation of both the insulating thimble and contained metallic sleeve having a centrally disposed indented area 102 and a slight terminal bulging 164 of the insulating material in line with the axis of applied pressure. However, irrespective of the mechanics of the deformation process utilization of the described tool results in desired deformation of the contained metallic sleeve 64 about the wires 68 to form a secure electrical and mechanical connection therebetween with a minimization, if not actual avoidance,

of destructive perforation of the surrounding insulating medium.

By way of further and more specific example, it has been found that the utilization of three workpiece deforming elements 30 is satisfactory for achieving the non-destructive deformation of pre-insulated fittings.

' For this three-element specific example, and as generally illustrated in FIGURE 3, a workpiece deforming element having the workpiece engaging surface 36 in the form of a sector of about 120 with a radius of about .187 inch, centered at a point disposed about 135 from the axis of the arm 32, and removed about .246 inch from the axis of rotation has produced eminently satisfactory results. In such a unit the diameter of an enclosed circle resulting from interengagement of the three workpiece deforming elements is about .113 inch plus or minus .005 inch. Such a unit has been found to readily accommodate and successfully deform preinsulated splice fittings sized to cover a range of wire sizes from about 1624 circular mils to 11,710 circular mils.

As also will be apparent to those skilled in this art, the above described wiping action type of deformation may be usefully employed in effecting deformation of varying types of workpieces and that the wiping surface configuration can be varied to suit the desired operations upon varying types of workpieces.

Having thus described my invention, I claim:

1. The method of making an electrical connection between a conductor and a fitting including an axially extending deformable metallic ferrule and a sleeve of extrudable insulating material surrounding said ferrule, said method comprising the steps of:

(a) inserting the end of said conductor into said ferrule, and

(b) deforming the fitting radially inwardly at a p111- rality of circumferentially spaced areas of the fitting to establish a plurality of concave portions in said fitting and to secure the conductor within the fitting by applying a force at each of a plurality of relatively small circumferentially spaced areas of the fitting, each said force having a radially inward component and a component tangential to one of said concave portions, each said force being of substantially the same magnitude and the tangential component of each said force being directed in generally the same circumferential direction, thus tending to rotate the fitting, and progressively increasing each said force while increasing the total area over which each said force is applied so portions of the insulating material are extruded in generally the same circumferential direction outwardly from each area to which a force is applied and portions of the ferrule are deformed inwardly to effect a mechanical and electrical connection between the ferrule and the conductor without perforation of the sleeve of insulating material.

2. The invention set forth in claim 1 wherein the forces are applied by a plurality of similar circumferentially spaced crimping dies each having a convex crimping surface which engage the fitting and wherein the area of each said crimping surface in engagement with the fitting increases as the forces are applied to the fitting.

References Cited by the Examiner UNITED STATES PATENTS 2,256,457 9/41 Douglas.

2,763,171 9/56 Modrey et al.

2,965,157 12/ Hoffman 29155.55 X 3,111,157 11/63 Henry.

WHITMORE A. WILTZ, Primary Examiner. JOHN F. CAMPBELL, Examiner. 

1. THE METHOD OF MAKING AN ELECTRICAL CONNECTION BETWEEN A CONDUCTOR AND A FITTING INCLUDING AN AXIALLY EXTENDING DEFORMABLE METALLIC FERRULE AND A SLEEVE OF EXTRUDABLE INSULATING MATERIAL SURROUNDING SAID FERRULE, SAID METHOD COMPRISING THE STEPS OF: (A) INSERTING THE END OF SAID CONDUCTOR INTO SAID FERRULE, AND (B) DEFORMING THE FITTING RADIALLY INWARDLY AT A PLURALITY OF CIRCUMFERENTIALLY SPACED AREAS OF THE FITTING TO ESTABLISH A PLURALITY OF CONCEVE PORTIONS IN SAID FITTING AND TO SECURE THE CONDUCTOR WITHIN THE FITTING BY APPLYING A FORCE AT EACH OF A PLURALITY OF RELATIVELY SMALL CIRCUMFERENTIALLY SPACED AREAS OF THE FITTING, EACH OF SAID FORCE HAVING A RADIALLY INWARD COMPONENT AND A COMPONENT TANGENTIAL TO ONE OF SAID CONCAVE PORTIONS, EACH SAID FORCE BEING OF SUBSTANTIALLY THE SAME MAGNITUDE AND THE TANGENTIAL COMPONENT OF EACH SAID FORCE BEING DIRECTED IN GEN- 